It has heretofore been proposed to roll upon and unroll door screens from a vertically disposed roller mechanism. Typical of such prior art are U.S. Pat. No. 4,651,797, Mar. 24, 1987 to A. E. Lange for ROLL-UP SCREEN DOOR; U.S. Pat. No. 5,758,704, Jun. 2, 1998 to C. K. Elrod for ROLL-UP SCREEN DOOR APPARATUS; and U.S. Pat. No. 5,505,244, Apr. 9, 1996 to P. A. Thumann for RETRACTABLE COVERING FOR A DOOR OPENING.
One significant deficiency of these screens is that the screen can only be in two stable states, namely fully retracted and stored upon the roll and fully extended and latched between two opposed door frames. Thus, for example, the door screen, which is spring biased to return to the roller could not be partly opened across the door opening between vertical door frames, for example, for the purpose of letting a person walk either in or out of a partly open sliding door alongside the screen. Alternatively for use with a pivoted door, the necessary fully open screen required by the prior art would permit insects, flies, etc. entry across the entire screen door width in order to let a person walk in or out of the door. This prior art is thus suited only generally for the purpose of retaining the screen fully closed or fully open while the doors are either closed or fully or partly opened.
Also the complexity of the structure and the tediousness of extending a rolled up screen across a door opening and latching it in place with these prior art mechanisms is not only costly, but is inconvenient and awkward.
There has been no satisfactory treatment in the prior art of screening French double doors having two sliding door panels so that the screen may be optionally viewed or hidden through the full length door glass, and so that the screen may be just partly opened for persons to pass through such a sliding door when partly opened.
Furthermore, known prior art mechanisms make it substantially impossible to secure the door opening against the entry of insects. In this respect there is insufficient protection against the entry of insects at the top and bottom of the screens, for example, if the screen were to flap or create gaps in the presence of a breeze or when touched by a person when opened.
Accordingly it is an objective of this invention to provide an improved simplified low cost, easy to install, screen accessory advantageous for use both with single doors and pivoted or sliding double doors configured to correct the foregoing prior art problems.
A more specific object of the invention is to employ screens more effectively to keep out insects as accompanying doors are opened and when the screens are fully withdrawn across the span of the door.
Another specific object of the invention is to provide a screen opening mechanism which permits the screen to reside stably in a partly open position.
Other objects, features and advantages of the invention will be found throughout the following description, drawings and claims.